You should be looking to achieve a conversion rate of about 1% - 3000 uniques = 30 sales.

If they are running an Affiliate Program that is worth anything, you should also have access to details of those sales transactions - either online or offline. That way you can see both the number of sales that have taken place and how that $60 is comprised.

If they cannot provide such information, I would be asking questions. Let's face it I bet they would not accept an invoice from a supplier without a breakdown of costs/charges.

This is precisely why I will not send traffic to any merchants trying to go down the cheapie route of using an independant Affiliate Program rather than an Affiliate Network.